Blood cells are divided into several distinct cell lines, including the erythroid cell line, the lymphoid cell line, and the myeloid cell line. Each line may include several different blood cell types, with (for example) the myeloid cell line including monocytes and granulocytes.
It has been demonstrated that the various blood cells descend from a single ancestor cell type, termed the hemopoietic stem cell. These stem cells differentiate into various distinct progenitor cells, and the progenitor cells in turn differentiate into the various types of mature cells found in blood. The various cell types involved in this system have been well studied in mouse and man: for example, a human hemopoietic stem cell is disclosed in U.S. Pat. No. 5,061,620 to Tsukamoto et al. Much less attention has been devoted to the study of avian species. See generally F. Dieterlen-Lievre et al., in The Avian Model in Developmental Biology: From Organism to Genes (Editions du CNRS 1990).
F. Cormier and F. Dieterlen-Lievre, Development 102, 279-285 (1988) shows that the wall of the chick embryo aorta harbors monocytic colony-forming cells, granulocytic colony-forming cells, granulocytic/monocytic colony-forming cells, and burst-forming erythroid units. The cells were isolated in a semi-solid (i.e., gelified) cell culture. Earlier hemopoietic progenitor cells were not isolated. See also F. Cormier et al., Developmental Biology 118, 167-175 (1986).
F. Cormier and F. Dieterlen-Lievre, Exp. Cell Res. 190, 113-117 (1990), describes long-term cultures of chicken hemopoietic bone marrow cells which establish a stromal layer and produce clonable precursors.
C. Nicolas-Bolnet et al., Exp. Cell Res. 196, 294-301 (1991), describes the developmental kinetics of monocytic colony-forming cells, granulocytic colony-forming cells, and granulocytic/monocytic colony-forming cells from the avian embryo spleen. This also employed a gelified cell culture. It was noted that no erythroid or multipotent progenitor cells could be developed in the culture system described. With the growth activities used, the colonies reach final maturation within three days.